1. Field of the Invention
The present invention relates to a method of detecting displacement of exposure position marks, which are provided for detecting displacement of an exposure position, during the manufacturing of a semiconductor or a thin-film magnetic head.
1. Related Art
When manufacturing a semiconductor, a thin-film magnetic head, or the like, a required conductive pattern or insulating layer pattern is formed by photolithography. During the manufacturing of such devices, when laminating a conductive pattern or insulating layer pattern, displacement of the pattern is detected, it is judged whether the exposure position is within a tolerated range, and the displacement is fed back to the exposure apparatus so that the exposure operation can be carried out with high precision.
Displacement of exposure position marks is detected by forming the exposure position marks at positions that do not affect the products, such as at the edges of a work, carrying out image recognition for the exposure position marks provided on a lower layer and an upper layer, and detecting the displacement between the exposure position marks.
Exposure position marks can have various shapes. FIGS. 6A and 6B show examples where displacement is detected using quadrangular exposure position marks. FIG. 6A shows an example where square patterns are used and FIG. 6B shows an example where bar-shaped patterns are disposed in a quadrangular arrangement. In FIG. 6A, a square pattern 6 formed in a latter process is formed as a larger square than a square pattern 5 that has been formed in a former process so that the square pattern 5 is positioned inside the square pattern 6. In FIG. 6B, patterns 8 formed in the latter process are disposed so as to surround bar-shaped patterns 7 that have been formed in the former process.
In either of FIGS. 6A and 6B, the center positions of the square patterns 5 and 6 and the center positions of the quadrangles surrounded by the bar shaped patterns 7 and 8 are respectively detected and the displacement of the exposure position is detected from the displacement of the center positions.    Patent Document 1
Japanese Laid-Open Patent Publication No. H11-126746    Patent Document 2
Japanese Laid-Open Patent Publication No. 2001-332466    Patent Document 3
Japanese Laid-Open Patent Publication No. 2003-243297